Using an older version of BUEX with 2012 agents

Is this possible, or will I have to manually uninstall all remote agents and load the old version back?

After weeks and weeks of pulling my hair out over 2012 I am giving up and building a new backup server using v12. I just need to know if I can start this during the week or if I'll have to schedule more weekend downtime to reboot almost 30 servers for RAWS.

I have used BackupExec since it was an Arcadia product, this is by far the worst backup software ever, with the possible exception of ARCServe.